WORCESTER — One person is in critical condition today after a boat slammed into a construction barge on Lake Quinsigamond about 1 this morning. Three other boaters were injured.

All four occupants of the boat were thrown from the craft, authorities said. They were rescued by a Fire Department dive team member, according to District Chief Samuel Richesson.

Wednesday afternoon, state Environmental Police identified the owner and operator of the boat as Gregory Polito of Shrewsbury. The agency did not release any more information about the crash and said it remains under investigation.

The barge is part of the ongoing construction of a new Kenneth F. Burns Memorial Bridge, which will span Lake Quinsigamond, linking Worcester and Shrewsbury. The contractor, Middlesex Corp., has a barge, a crane and other construction equipment in the area.

Worcester police believe a safety light on the barge might have been out in the area where the boat hit the barge. The crash remains under investigation, a police spokesman said this morning.

Authorities have not released the other boaters' names, but said the person with the most serious injuries is a 28-year-old man from Millbury. He has head, facial and internal injuries and is in critical condition at UMass Memorial Medical Center — University Campus.

The other injured boaters are a 50-year-old man from Shrewsbury, a 49-year-old woman from Shrewsbury and a 26-year-old woman from Northbridge. Their conditions were not immediately known.

Accident reconstruction investigators were at the lake with Environmental Police this morning. District Chief Richesson said rescuers were challenged by the steep slope at the back of the property leading into the water. They were also delayed by a locked gate to the site that firefighters had to force open.

It took about 20 minutes to rescue the boaters. The accident was reported by one of the men on the boat.

This morning, a construction crane from the bridge project was used to pull the boat from the water.